Apparatus for calculating decision parameters in an IMT-2000 system

ABSTRACT

Improved techniques for calculating decision parameters in an IMT-2000 system is disclosed. In an apparatus for calculating decision parameters, there is provided a correlation value calculation unit having a number of correlation value calculators, each of which calculates a correlation value between selected information that is selected at the mini-slot selection unit and one of capable input signals. In order to selectively operate the correlation value calculators, there is provided a correlation circuit control unit controlling the operation of each of the correlation value calculators by using each of the comparison between the received correlation value to a predetermined threshold value. Accordingly, the power consumption of the correlation value calculators is reduced. And, the decision parameter is selected from the decision parameters previously selected during the divided monitoring section, thereby enabling high-speed cell search.

FIELD OF THE INVENTION

The present invention relates to an apparatus for calculating decisionparameters in an IMT-2000 system, and, more particularly, to anapparatus for calculating decision parameters with low power consumptionand a high-speed cell search.

DESCRIPTION OF THE PRIOR ART

Generally, at a code position modulation (CPM) type of W-CDMA system, aposition of a synchronization signal (a synchronization code) which isused to perform a base station discrimination, a mobile stationsynchronization and a high-speed cell search, is differently modulatedaccording to each of base stations and transferred to each of receivers.

The synchronization code of a forward directional synchronizationchannel adapted by the CPM type consists of one binary code having alength of 256 chips. One synchronization code is transmitted accordingto each of slots. Wherein, one frame is a length of 2560 chips and oneframe has 16 slots. Each of the slots is divided into a number ofmini-slots. The length of the mini-slot is represented by δ that is apositive integer and a changeable parameter according to a need ofsystem operation.

In addition, the position of the synchronization code inserted to eachof the mini-slots is given to a value coinciding with each code elementof a time hopping code corresponding to a long code group of a currentbase station. The length of the time hopping code used herein is 16being equal to the length of slot number of each frame. The magnitude ofalphabet M of each time hopping code is equal to or less than the numberof mini-slots in a slot.

On the other hand, at a transmitting unit, the position of thesynchronization code adapted by the CPM type is modulated andtransmitted. A receiving unit (a CPM receiver) receives the modulatedand transmitted position and detects base station group information.

FIG. 1 shows a schematic diagram of a high-speed cell searching processof a prior art of a CPM type of W-CDMA system.

At first step, a start point of a mini-slot is detected by using asynchronization channel match filter.

And then, at second step, both long code group information and a startpoint of 10 ms frame are detected by using the output value of the matchfilter at each mini-slot clock position (i.e., each δ chip) after thestart point of the mini-slot.

Finally, the long code start point information is used to determine thetype of the long code.

The detailed description of the second step is as follows.

For example, in case that the number of the long code group used at thesystem is 2 and the number of each of the slots is 4, a decisionparameter is calculated as follows.

Long code group number=2

Slot number per frame=4

Mini-slot number=Skip code alphabet magnitude=5

Skip code for group 1=(1 3 3 4)

Skip code for group 2=(4 2 0 1)

Total code/shift collection=(1 3 3 4) (4 1 3 3) (3 4 1 3)(3 3 4 1)(4 0 21)(1 4 0 2)(2 1 4 0) (0 2 1 4)

Time shift (slots)=0 1 2 3

As shown in above example, a CPM receiver calculates decision parametersfor 8 (2×4) code group shift collections based on the slot start pointof the matched filter. The decision parameters are correlation valuesbetween an input code and all of group information codes. The largestdecision parameter is a group information code having a largestcapability. The group information code is used to calculate a startpoint of the frame.

For one mini-slot, L (Code group number×Slot number per frame) decisionparameters are calculated. The mini-slot number N is determinedaccording to a required system performance and a used circumstance.

FIG. 2 shows a block diagram of a prior art of a CPM receiver.

As shown in FIG. 2, a mini-slot selection unit 10 selects a suitablemini-slot position at an inputted synchronization channel. Each of theselected suitable mini-slot positions is provided to each of decisionparameter calculators 21, 22 and 20+N contained at a decision parametercalculation unit 20 through each of lines L2, L4 and L6.

Each of the decision parameter calculators 21, 22 and 22+N calculates acorrelation value between each input and all of the group informationcodes provided from line L8. Each output from each of the calculators21, 22 and 22+N is provided to a decision parameter selection unit 30.

The decision parameter selection unit 30 selects required informationamong the inputted decision parameters.

In general, the required information selected at the decision parameterselection unit 30 is comprised of a set of several decision parametershaving a largest value. At this time, the decision parameter calculationunit 20 continues a calculation process that does not effect the finaldecision parameter selection determination.

Since, however, the decision parameter calculation unit of the prior CPMreceiver continues the calculation process after the decision parameterselection unit selects the required information, a consumption power ofthe receiver is increased.

SUMMARY OF THE INVENTION

It is, therefore, a primary object of the invention to provide to anapparatus for calculating decision parameters with low power consumptionand a high-speed cell search.

To achieve the above object, in one embodiment of the present invention,an apparatus for calculating decision parameters in an IMT-2000 system,the IMT-2000 system having a mini-slot selection unit for selecting amini-slot position wherein a decision parameter is selected and adecision parameter selection unit for selecting one decision parameterfrom the calculated decision parameters, said apparatus comprises: acorrelation value calculation unit having a number of correlation valuecalculators, each of which calculates a correlation value betweenselected information that is selected at the mini-slot selection unitand one of capable input signals; and a correlation circuit control unithaving a number of correlation circuit controllers each of whichreceives a correlation value from a corresponding one of the correlationvalue calculators and compares the received correlation value to apredetermined threshold value during a predetermined monitoring section,and controlling the operation of each of the correlation valuecalculators by using each of the comparing results.

Wherein, the predetermined monitoring section is obtained by dividing atotal monitoring section of each of the correlation value calculators,and said threshold value is determined in order to determine whether oneof the correlation value calculators operates or not during the totalmonitoring section.

To achieve the above object, in another embodiment of the presentinvention, an apparatus for calculating decision parameters in anIMT-2000 system, the IMT-2000 system having a mini-slot selection unitfor selecting a mini-slot position wherein a decision parameter isselected and a decision parameter selection unit for selecting onedecision parameter from the calculated decision parameters, saidapparatus comprises: a correlation value calculation unit having anumber of correlation value calculators, each of which calculates acorrelation value between selected information that is selected at themini-slot selection unit and one of capable input signals; and a rankingdetermination unit receiving each of correlation values provided fromeach of the correlation value calculators during a predeterminedmonitoring section, ranking the correlation values and selectivelyoperating the correlation value calculators according to the rank of thecorrelation values.

Wherein, the predetermined monitoring section is obtained by dividing atotal monitoring section of each of the correlation value calculators,and wherein said ranking determination unit operates a predeterminednumber of high ranked correlation value calculators and stops theoperation of the other correlation value calculators that are not highranked during a remaining total monitoring section.

The advantages of the invention are numerous. One of advantage of theinvention is that a number of correlation value calculators that do noteffect the decision parameter selection are not operated during theremaining monitoring section by using the threshold comparison techniqueand the correlation value ranking technique to reduce the powerconsumption of the correlation value calculators.

Another advantage of the invention is that the decision parameter isselected from the decision parameters previously selected during thedivided monitoring section, thereby enabling high-speed cell search.

These and other features of the present invention are more fully shownand described in the drawings and detailed description of thisinvention. It is to be understood, however, that the description anddrawings are for the purpose of illustration and should not be read in amanner that would unduly limit the scope of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the instant invention willbecome apparent from the following description of preferred embodimentstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a high-speed cell searching process ofa prior art of a CPM type of IMT2000 system;

FIG. 2 shows a block diagram of a prior art of a CPM receiver of IMT2000system;

FIG. 3 describes a block diagram of a decision parameter calculationapparatus of IMT2000 system in accordance with a first embodiment of thepresent invention; and

FIG. 4 illustrates a block diagram of a decision parameter calculationapparatus of IMT2000 system in accordance with a second embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention will now be described indetail, with reference to the accompanying drawings.

The decision parameter calculation unit in accordance with the presentinvention utilizes a threshold value technique or a ranking technique.

<Embodiment 1>

FIG. 3 describes a block diagram of a decision parameter calculationunit of IMT2000 system in accordance with a first embodiment of thepresent invention.

As shown in FIG. 3, a reference numeral 100 denotes a correlation valuecalculation unit having a number of correlation value calculators 101,102 and 100+N. Each of the correlation value calculators 101, 102 and100+N calculates a correlation value between selected information thatis selected at the mini-slot selection unit (reference numeral 10 ofFIG. 2) and one of capable input signals.

Also, a reference numeral 200 denotes a correlation circuit control unit200 having a number of correlation circuit controllers 201, 202 and200+N. Each of the correlation circuit controllers 201, 202 and 200+Nreceives a correlation value from a corresponding one of correlationvalue calculators 101, 102 and 100+N and compares the receivedcorrelation value to a predetermined threshold value during apredetermined monitoring section. By using each of the comparingresults, each of the correlation circuit controllers 201, 202 and 200+Ncontrols the operation of a corresponding correlation value calculator.

The operation of the first embodiment is as follows.

Firstly, each output from the mini-slot selection unit 10 of FIG. 2 isprovided to a corresponding one of correlation value calculators 101,102 and 100+N contained at the correlation value calculation unit 100.

And then, each of the correlation value calculators 101, 102 and 100+Ncalculates the correlation value between the inputted value and one ofthe capable input signals to provide the calculated correlation value toa corresponding one of the correlation circuit controllers 201, 202 and200+N contained at the correlation circuit control unit 200.

Each of the correlation circuit controllers 201, 202 and 200+N containedat the correlation circuit control unit 200 compares the predeterminedthreshold value (H1) to an inputted correlation value during a dividedmonitoring section (T1) that is divided from a prior monitoring section(T). The threshold value is a value by which the correlation valuecalculator is operated or not during the monitoring section (T).

In case that the inputted correlation value is larger than the thresholdvalue (H1), a corresponding correlation calculator is operated duringthe monitoring section (T). In case that the inputted correlation valueis not larger than the threshold value (H1) during the dividedmonitoring section (T1), a corresponding correlation calculator is notoperated during a remaining section, i.e., the section between the T1and T.

For example, a correlation circuit controller 201 compares a correlationvalue from the correlation value calculator 101 to a predeterminedthreshold value (H1) during a divided monitoring section (T1). In casethat the correlation value is larger than the threshold value (H1), thecorrelation circuit controller 201 enables the correlation valuecalculator 101 to be operated during the monitoring section (T). In casethat the correlation value is not larger than the threshold value (H1),the correlation circuit controller 201 enables the correlation valuecalculator 101 to be not operated during a remaining section, i.e., thesection between T1 and monitoring section (T).

Similarly, each of the remaining correlation circuit controllers 202 and2000+N performs the same operation as the correlation circuit controller201.

Since, therefore, each of the correlation value calculators 101, 102 and100+N is selectively operated or not according to the threshold value,only the correlation value calculators having a condition that adecision parameter is larger than the threshold value, operates duringthe monitoring section (T) and other correlation value calculatorshaving a condition that a decision parameter is not larger than thethreshold value, does not operate after the divided monitoring section(T1). Accordingly, the power is not consumed during the remainingmonitoring section between T1 and T to reduce the power consumption.

<Embodiment 2>

FIG. 4 illustrates a block diagram of a decision parameter calculationapparatus in accordance with a second embodiment of the presentinvention.

As shown in FIG. 4, a reference numeral 300 denotes a correlation valuecalculation unit having a number of correlation value calculators 301,302 and 300+N. Each of the correlation value calculators 301, 302 and300+N calculates a correlation value between selected information thatis selected at the mini-slot selection unit (reference numeral 10 ofFIG. 2) and one of capable input signals.

Also, a reference numeral 400 denotes a ranking determination unit thatreceives each of correlation values provided from each of thecorrelation value calculators 301, 302 and 300+N a, ranks thecorrelation values and selectively operates the correlation valuecalculators 301, 302 and 300+N according to the rank of the correlationvalues.

The operation of the second embodiment is as follows.

Firstly, each output from the mini-slot selection unit 10 of FIG. 2 isprovided to a corresponding one of correlation value calculators 301,302 and 300+N contained at the correlation value calculation unit 300.

And then, each of the correlation value calculators 301, 302 and 300+Ncalculates the correlation value between the inputted value and one ofthe capable input signals to provide the calculated correlation value tothe ranking determination unit 400 and the decision parameter selectionunit 30 of FIG. 2.

The ranking determination unit 400 ranks the inputted correlationvalues, each of which is calculated during a divided monitoring sectionT1, and operates I number of correlation value calculators that are highranked. The other correlation value calculators that are not highranked, are not operated.

For example, in case that there are five correlation value calculators#1, #2, #3, #4 and #5, the ranking is in a sequence #2, #3, #1, #5, #4during the divided ranking section (T1), and the number of thecorrelation value calculators to be operated is 3, the rankingdetermination unit 400 operates three correlation value calculators #2,#3 and #1 during the monitoring section (T) and does not operate theremaining correlation value calculators #5 and #4 during the monitoringsection (T).

Since, therefore, each of the correlation values is detected and rankedduring the divided monitoring section (T1) and only a predeterminednumber of high ranked correlation value calculators is operated during aremaining monitoring section, the power consumption can be reduced.

The advantages of the invention are numerous. Different embodiments orimplementations may yield one or more of the following advantages. Oneof advantage of the invention is that a number of correlation valuecalculators that do not effect the decision parameter selection are notoperated during the remaining monitoring section by using the thresholdcomparison technique and the correlation value ranking technique toreduce the power consumption of the correlation value calculators.

Another advantage of the invention is that the decision parameter isselected from the decision parameters previously selected during thedivided monitoring section, thereby enabling high-speed cell search.

Although the preferred embodiments of the invention have been disclosedfor illustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims.

1. An apparatus for calculating decision parameters in an IMT-2000system, the IMT-2000 system having a mini-slot selection unit forselecting a mini-slot position said apparatus comprising: a correlationvalue calculation unit having a number of correlation value calculators,each of which calculates a correlation value between selectedinformation that is selected at a mini-slot selection unit and one ofinput signals; and a correlation circuit control unit having a number ofcorrelation circuit controllers each of which receives a correlationvalue from a corresponding one of the correlation value calculators andcompares the received correlation value to a predetermined thresholdvalue during a predetermined monitoring section, wherein one ofcorrelation values is equal to or greater than the threshold value isselected as a decision parameter, and wherein only the correlation valuecalculator having a larger value than the threshold value in themonitoring section calculates the correlation value.
 2. The apparatus asrecited in claim 1, wherein the predetermined monitoring section isobtained by dividing a total monitoring section of each of thecorrelation value calculators.
 3. An apparatus as recited in claim 2,wherein said threshold value is determined in order to determine whetherone of the correlation value calculators operates or not during thetotal monitoring section.